All KKM barrels are made using certified 416R gun-barrel quality stainless steel bar stock. These barrels are then heat treated and vacuum tempered to 42 RC. All of our barrels are CNC machined to obtain superior dimensional tolerances over stock. Because of our advanced proprietary button rifling process, all KKM barrels offer greater accuracy over stock barrels. Our Glock barrels come with fully supported SAAMI spec. match chambers for shooting factory or reloaded ammunition. Converts from .40 to 9mm. These are drop-in barrels, no fitting or machining required.